1. Field of the Invention
This invention generally relates to an image processor such as a copying machine or a scanner functioning to read images of an original represented on a paper sheet or the like and then to subject these images to various kinds of processing and more particularly to a take-up pulley mounted on a driving shaft in such image processor to take up/let out the wire operatively associated with a carrier adapted to scan the original and thereby to transmit a drive force from an electric motor to said carrier.
2. Description of the Related Art
The function of the carrier in the image processor is to pick up images to be processed from the original and to guide them to an image processing unit such as a CCD. To achieve this, the carrier is provided with a reflector or the like adapted to form an optical path extending from the original to said CCD. The carrier thus scans the original and picks up the images on said original. The carrier is operatively associated with a wire taken up on a pulley by motor power so that said scanning is performed as said wire travels. One end of the wire is attached to the inner wall of the housing containing said carrier. The other end of the wire is also attached to the inner wall of the housing but with interposition of a tension spring, for example, in the form of a tension coil spring so that the tension spring puts the wire under a tension required for properly driving the carrier. An intermediate length of the wire is fixed directly on the carrier or extended around guide pulleys which are rotatably supported by the carrier. Said intermediate length of the wire is also wound around said take-up pulley by a desired number of turns.
FIG. 6 is a side view showing an example of a conventional take-up pulley 50 shown partially in cross-section. As shown, this take-up pulley 50 of prior art comprises a drum-like section 51 on which the wire is taken up and a boss 52 formed at one end of said drum 51. The drum 51 is formed at its axially opposite ends with stopper flanges 53, respectively, in order to prevent the wire (not shown) wound around said drum 51 from slipping off. This prior art take-up pulley 50 is formed by machining metallic material or made of sintered metal.
However, the take-up pulley 50 of the prior art, made of metallic material or sintered metal, necessarily leads to a high manufacturing cost of the pulley itself and a correspondingly high manufacturing cost of the image processor as a whole. To overcome this cost problem, it has been proposed to mold the take-up pulley of a suitable synthetic resin material.
FIG. 7 illustrates a mold construction which has been adopted to make the take-up pulley by molding a suitable synthetic resin material. As illustrated therein, the mold consists of a pair of split mold sections 54a, 54b adapted to be opened radially of the drum 51 so axially opposite ends of the drum 51 can be formed with said stopper flanges 53. Such arrangement of the mold is inevitably accompanied with the problem that a desired out of roundness may not be ensured for the drum 51.